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<p><em>IfcLagTime</em> describes the time parameters that may exist within a sequence relationship between two processes.</p>

    <p>
      An <em>IfcLagTime</em> provides information about the
      time lag that exists between the predecessor and successor
      process in a sequence. The assertion of the time lag is
      optional for a sequence but for work schedules that
      specifically deal with processes occurring at particular
      times, it should be asserted.
    </p>
    <p>
      A lag time has a duration type. This allows the
      identification of whether elapsed time or work time is
      being measured (where work time is the estimate of the time
      required to complete the process and elapsed time being the
      amount of time actually allocated to the process)
    </p>
    <p>
      The form of measurement of the duration can be captured.
      Allowed values for this are MEASURED, PREDICTED or
      SIMULATED. The selection of this value depends on the use
      of the schedule. A NOTDEFINED value is also allowed.
    </p>
    <p>
      The value of the time lag may be selected as being either a
      percentage ratio or an actual time measure. If selected as
      a ratio, the percentage should apply to the duration of the
      predecessor process (relating process) such that e.g. a
      value of 0.5 (50%) would indicate that the successor task
      should start when the predecessor task is 50% complete (if
      a START-START sequence type is used) or should wait for 50%
      of the duration of the predecessor process to have elapsed
      after the finish of the predecessor process in case of a
      FINISH-START sequence type.
    </p>
    <p>
      The time unit for the task duration may also be set and
      this may be set to any allowed unit of time measure.
    </p>

<blockquote class="history">
HISTORY&nbsp; New entity in IFC4.
</blockquote>

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